Electrostatic precipitators



Feb. 4, 1958 w. J. Roos El' AL ELECTROSTATIC PRECIPITATORS Filed Aug. zo, 1255 4 POWER 2O ff PACK 4 ,Eal L. Zzelzazdia Y zz/ezzvzi l by Maag United states Patent O ELECTROS'I'ATIC PRECIPITATORS William J. Roos, Sharon, and Earl L. Richardson, Hyde Park, Mass., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Penn- Sylvania Application August 30, 1955, Serial No. 531,416

2 Claims. (Cl. 183-7) This invention relates to electrostatic precipitators for removing small foreign particles such as dust from gases such as air.

Intermeshed dielectric laments such as are used in mechanical filters of the glass and fibre wool type, are easily given electrostatic charges, and many attempts have been made to use them commercially as electrostatic precipitators. They are, however, erratic in that they will not hold a uniform electrostatic charge. Often they are charged to too high a voltage so that sparks occur therein, or to too low a voltage for effective collection. This invention instead of permitting such a filter to float in an electrostatic field where it would assume an uncontrolled charge, connects an electric resistor through which the ionization current is caused to flow, across the filter so that the voltage drop in the resistor determines accurately the charge on the filter, and maintains a uniform charge.

An object of this invention is to improve the methods of applying electrostatic charges to filters of dielectric filaments.

This invention will now be described with reference to the annexed drawings, of which:

Fig. 1 is a side section of an electrostatic precipitator embodying this invention, and

Fig. 2 is a section along the line 2--2 of Fig. l.

A rectangular metal casing has an open air inlet end l1 and `an opposite open air outlet end 12. A mat 13 of dielectric filaments, preferably of the glass wool type, has a meshed metal wire screen 14 in contact with its downstream side, and has a similar screen 15 in contact with its upstream side. The downstream screen is grounded to the casing 10 while the upstream screen is insulated from the casing by the insulating plates 16 which extend between its ends and the casing.

The insulating plates 16 extend from the mat 13 towards the air inlet 11, and have secured to their inner sides, the metal ionizer plates 17, insulating such plates 17 from the casing. An ionizer wire 18 is supported by a pair of insulators 19 from opposite side walls of the 2,822,058 Patented Feb. 4, 1958 ice casing midway between the metal plates 17 which are non discharging ionizer electrodes.

'I'he ionizer wire 18 is connected to the positive highvoltage terminal of a conventional power pack 20, the negative terminal of which is grounded. The upstream screen 15 is connected to the metal plate 17 and to one end of a variable resistor 21, the other end of which is connected to the downstream screen 14 and to ground.

In operation, ionization current instead of owing between an ionizer wire and its grounded non-discharging ionizer electrodes as usually occurs, flows to the plates 17 and through the series resistor 21 to ground. This resistor has its ends connected to the upstream and downstream screens 15 and 14 respectively, so that the voltage drop across it is the voltage across the mat 13. This voltage remains substantially constant since using a regulated power pack, the ionization current remains substantially constant.

The dust particles in the air to be cleaned are given positive electrostatic charges as they pass between the ionizer wire 18 and the metal plates 17, and are collected by the electrostatically charged mat 13.

What we claim as our invention is:

1. An electrostatic precipitator comprising a mat of dielectric filaments, metal screens on opposite sides of said mat, an electric resistor connected at its ends to said screens, an ionizer wire, non-discharging ionizer electrodes on opposite sides of said wire, means connecting said electrodes to one of said screens, a high voltage, direct current power supply, means for connecting said wire to a terminal of said supply having one polarity, and means connecting said other screen to a terminal of said supply having the opposite polarity.

2. An electrostatic precipitator comprising a metal casing having an open air inlet and an open air outlet, a mat of dielectric filaments extending cross-wise said casing between said inlet and outlet, a metal screen between said mat vand said outlet in contact with said casing, a second metal screen between said mat and said inlet, said second screen being insulated from said casing, an ionizer wire insulatedly supported from said casing, non-discharging ionizer electrodes on opposite sides of said wire, means insulatedly supporting said electrodes from said casing, an electric resistor connected at its ends to said screens, a high voltage, direct current power supply, means connecting said wire to a positive high voltage terminal of said supply, and means connecting said casing to the negative terminal of said supply.

References Cited in the file of this patent UNITED STATES PATENTS 2,297,601 Williams Sept. 29, 1942 2,579,441 Palmer Dec. 18, 1951 2,579,445 Warburton Dec. 18, 1951 

